1. Field of the Invention
This invention relates to vane pumps, and more particularly to a vane pump having a rotor rotatably mounted in a casing, an outer peripheral wall of the rotor and an inner peripheral wall of the casing opposed to the outer peripheral wall being shaped cylindrical, the rotor having an axis of rotation offset from the center of the inner peripheral wall of the casing, and a plurality of vanes mounted in the rotor and projecting variable amounts from the outer peripheral wall of the rotor, the vanes being revolvable with rotation of the rotor, with distal ends of the vanes movable along the inner peripheral wall of the casing.
2. Description of the Related Art
Conventionally, the vanes have spring-loaded proximal ends for strongly pressing distal ends thereof against the inner peripheral wall of the casing. However, the vanes and the inner wall of the casing tend to wear through sliding contact with each other. The springs also tend to break through fatigue. Thus, the conventional vane pump has a disadvantage with respect to durability.